Great project and build. I wonder if using a small fan would not help energy transmission, which is eventually the goal of cooking. It may also make the oven work like it’s at higher température while not consuming much energy. It would discharge energy from the walls faster using convection in addition to radiation.

Plus, you can experiment with tray materials depending on what you want to cook.

Suggestions inspired by my experience with convection/classic oven and copper pizza plates

https://www.italiancookshop.com/products/hammered-copper-rou...